Grade 10 CBC Chemistry | Electron configurations 1 to 20: s and p notation, Hund's rule, 2.8.8.1

Why is potassium 2.8.8.1 and not 2.8.9? In this Grade 10 CBC Chemistry lesson you will learn the three rules that decide where every electron goes (lowest energy first, the Pauli principle and Hund's rule), draw orbital boxes, and write the s and p notation, such as 1s² 2s² 2p⁶ 3s¹, for every element from hydrogen to calcium. You will also turn the notation into the arrangement, check your answers, work backwards to name an element, count unpaired electrons and find mistakes. A FREE REVISION PAPER FOR THIS LESSON Paper 1: Core concepts Download them here: https://drive.google.com/file/d/1VCV9... The marking scheme will be in the description of the first video of Playlist 2, so try the paper on your own first. MARKING SCHEME FOR VIDEO 3 Did you try the revision papers from Video 3 (s and p orbitals)? Mark your work here: https://drive.google.com/file/d/1uFJX... IN THIS VIDEO 0:00 Hook and title 0:35 In this video 1:21 Reading the notation 2:01 Rule 1: lowest energy first 2:56 Rule 2: the Pauli principle 3:22 Rule 3: Hund's rule 4:21 When to spread out, when to pair 5:08 Hydrogen to beryllium 6:01 Boron to nitrogen: Hund's rule at work 7:05 Oxygen to neon: pairing up 7:57 Sodium to argon: the pattern repeats 9:12 Potassium and calcium: 4s 10:22 From notation to arrangement 11:05 The method, and two checks 11:51 Worked example: phosphorus 12:48 Your turn: sulphur 13:39 Working backwards 14:38 Your turn: work backwards 15:35 Counting unpaired electrons 16:32 Find the mistake 17:36 Your turn: find the mistake 18:40 Elements 1 to 20 at a glance 19:02 Watch out for these mistakes 19:55 What to remember 20:40 Challenge and next playlist YOUR CHALLENGE Two elements from 1 to 20 have exactly three unpaired electrons. Which two are they? Write their s and p notation in the comments. PREVIOUS VIDEO Video 3: s and p orbitals:    • Grade 10 CBC Chemistry | s and p orbitals:...   NEXT This is the last video in Playlist 1: The Atom. Playlist 2 (Ions, formulae and equations), Video 1: How atoms form ions. We use these arrangements to see why atoms lose or gain electrons. Coming soon. ABOUT SP-SciLearn SP-SciLearn makes paced, interactive science lessons for Kenyan learners following the CBC. Every video stops so that you can try a question yourself before the answer appears. Subscribe and turn on notifications so that you do not miss the next lesson. Grade 10 CBC Chemistry · 1.2 The Atom #Grade10Chemistry #CBCKenya #Chemistry